Washington -LRB- CNN -RRB- -- Lone individuals are the most likely to launch attacks in the United States following the death of al Qaeda leader Osama bin Laden , according to a joint Department of Homeland Security/FBI bulletin sent to state and local law enforcement .

The advisory says lone offenders who share al Qaeda 's ideology are the greatest near-term threat because they are `` unburdened by organizational constraints that can slow operational decisions by established terrorist groups . ''

Individuals could try to attack low-security targets using simple improvised explosive devices or small arms , the message said . However , the May 9 advisory obtained by CNN notes that federal law enforcement officials have `` no credible information to suggest that a specifically targeted plot is underway . ''

The document cited the vow in the al Qaeda statement confirming the death of bin Laden which said `` the soldiers of Islam '' would continue to plan attacks . The advisory also says over the past year , Inspire magazine -- published in English by al Qaeda in the Arabian Peninsula -- and various jihadi spokesmen have said attacks by individuals `` can have a significant impact . ''

The notice mentions several attacks involving a single perpetrator , including the November 2009 Fort Hood attack that left 13 people dead . Army Major Nidal Hasan is accused in that shooting .

Law enforcement officials have repeatedly warned that plots by lone wolves are the most difficult to detect and disrupt . But the DHS/FBI bulletin urges state and local law enforcement officials to be on the lookout for suspicious activity .

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Plots by ` lone wolves ' are difficult to detect and disrupt , officials say

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An Army major is accused in the Fort Hood shooting that left 13 people dead

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There is no information suggesting a specific plot at this time , the advisory says